Spiral conveyors



P 1962 G. E. SMITH EITVAL 3,055,550

SPIRAL CONVEYORS Original Filed June 15, 1959 Inventors G-EORGE E..S'YMITH RiCHARD- CHANTLER v gzdw fl United States Patent M 3,055,550SPIRAL CONVEYORS George Egerton Smith and Richard Chantler, Galleywood.End, Chelmsford, England, assignors to Egerton Smith Engineers Limited,Chelmsford, England, a company of Great Britain Original applicationJune 15, 1959, Ser. No. 820,368. Divided and this application June 21,1960, Ser. No. 37,752 Claims priority, application Great Britain June20, 1958 4 Claims. (Cl. 222-52) This invention relates to spinal feedconveyors more particularly to such conveyors for feeding pulverulentmaterial suspended in liquid.

The invention is particularly applicable to the drive of an Archimedeanspiral conveyor for feeding a mixture of a pulverulent material carrierin a liquid, e.g. sand in water, through a nozzle. In such spiralconveyor mechanisms the shaft of the spiral, which rotates in a conveyorhousing fed by a hopper, is driven from a prime mover such as anelectric motor and it is frequently necessary for the feed to beconstantly watched and the speed of drive adjusted to ensure that thespiral conveyor is not overloaded and that the flow of material fed ismaintained at a desired rate.

This application is divided out of United States Serial No. 820,368which discloses control devices for machines and mechanisms having amember responsive to a predetermined load on the machines or mechanismsso as to actuate a device for recording the load or to initiatevariation of the operation of the machine or mechanism responsive to theload thereon. By a recording device is meant a device, apparatus orinstrument which will record the strain in the strainable member andhence the load on the machine or mechanism being controlled, or a deviceor apparatus which when the strainable member is strained to one or morepredetermined values will cause actuation of means to stop the powerinput to the machine or drive mechanism being controlled or the outputload thereon, or modify or reverse the power input thereto or the outputload thereon.

The control device of United States Serial No. 820,368 comprises atleast one twistable bar element having a portion fixable againstrotation about its longitudinal axis and, spaced along said axis fromthe fixed portion, a portion operatively connected to a displaceableelement of the mechanism which is capable of relative movement withrespect to a part of the mechanism movable under load, the bar elementbeing calibrated to restrain movement of the displaceable element whenthe loadable part of the mechanism is loaded within at least onepredetermined limit, but when said load exceeds said limit will twistthereby permitting relative movement directly proportional to said loadof the displaceable element with respect to said loadable part, one ofsaid elements having means associated therewith for connection to arecording device. The device can be employed to operate by twisting ofthe bar element when the mechanism is loaded to predetermined limits ofmaximum and minimum permitted load.

The twistable portion of the bar element is preferably provided with aprojection which may be radial engaging in a .slot or the like in thedisplaceable element. The con trol device preferably comprises anelongated torsion bar fixed against axial rotation towards one endthereof, a

3,055,550 Patented Sept. 25, 1962 connection towards the other end ofthe torsion bar between the torsion bar and a displaceable elementshaped to form a driving member of a mechanism to be controlled, theshape of the torsion bar and the connection between the torsion bar andthe displaceable element being such that when the mechanism is loadedwithin a predetermined limit it will hold the displaceable memberagainst displacement, but when the load on the mechanism reaches thepredetermined limit the torsion bar will twist, the torsion bar beingprovided with means for association with a recording device responsiveto twisting of the torsion bar.

The recording device may be operatively connected to means for impartingthe drive to the driven member, said means being associated with asecond control device so that when the displaceable element reaches thelimit of its predetermined movement the torque imparted to the drivingmember is varied or reduced to zero. The movement of the displaceablemember may be in either direction, the torque imparted to the drivingmember being varied, reduced to Zero or reversed so that the load on thegear mechanism is reduced within predetermined limit or eliminated.

The displaceable element or the bar element may be provided with stopmeans to limit its movement, or be provided with limits in oppositesenses so that the drive is alternately reversed from one direction toanother to cause oscillation of a member to be controlled.

The object of the present invention is to provide a drive transmissionfrom a prime mover to a driven member, in this case a spiral conveyor,which incorporates a control device operating to adjust automatically,to within predetermined upper and lower limits, the torque imparted tothe driven member by the prime mover.

According to the present invention a conveyor app-aratus, forpulverulent material suspended in liquid, comprises a tubular conveyorcasing, a rotatable spiral conveyor member within the casing, a hoppersupplying the material to be conveyed to one end of the conveyor memberwithin the casing, a variable outlet orifice in the region of the otherend of the casing, means operable to vary the size of said orifice, adrive member for rotating the conveyor member in the casing, andassociated with said elements a control device comprising at least onetwistable bar element having a portion fixable against rotation withrespect to one of said members about its longitudinal axis and spacedalong said axis from the fixed portion, a portion operatively connectedto a displaceable element capable of relative movement with respect tothe other of said members, the bar element being calibrated to restrainmovement of the displaceable element when said members are loaded withinat least one predetermined limit, but when said load exceeds said limitwill twist thereby permitting relative movement of one of said memberswith respect to the other member in direct proportion to said excessload, and means associated with said displaceable element and saidorifice varying means so as to vary the size of said orifice to causereduction of the load on said members to within said predeterminedlimit.

Preferably said bar element is calibrated to restrain movement of saiddisplaceable element when said members are loaded within upper and lowerpredetermined limits and to twist when the load on said membersrespectively falls below or exceeds said limits to cause variation ofthe size of said orifice and maintain the load on said members withinsaid limits.

The orifice in the casing in a preferred construction is formed by aninflatable annular tube secured to the open delivery end of the casing,a pump operable to pump fluid into said tube and to release the fluidfrom said tube, a control valve between said pump and said tube andresponsive to movement of the displaceable element so as to vary thesize of the orifice by controlling the amount of fluid in said tube.

In order that the invention may be more clearly understood someconstructions in accordance therewith will now be described, by way ofexample, with reference to the accompanying drawings, in which:

FIGURE 1 is a partial crosssection of a transmission drive; and

FIGURE 2 is a diagrammatic side view partly in crosssection of apulverulent spiral conveyor feed embodying the drive transmission shownin FIGURE 1.

In the drawings the same references are used to designate the sameparts.

The drive transmission shown in FIGURE 1 comprises a driving member inthe form of a shaft 1 and a driven member shown as a shaft 2 coupledtogether as at 3 in a conventional manner so that one can rotaterelative to the other. The shaft 2 is preferably short as shown and hasa keyway 2a for connection to the output shaft of the prime mover. Theshaft 2 carries a flange 4 having a number of circular bores 5 thereinof which one is shown while the shaft 1 has an annular flange 6 ofsmaller diameter than the flange 4 and having therein one radial slot 7in radial alignment with each bore 5 in the flange 4. A circular plate 8is fixed to the shaft 2 and has a number of holes 9 each aligned axiallywith one of the bores 5 in the flange 4, each hole 9 having anon-circular cross-section, for example, square.

A number of torsion bars, of which one is shown at 10 in FIGURE 1, areprovided each with a squared end 11 fixed in one of the holes 9 andpassing freely through the aligned bores 5 of the flange 4; each bar 10carries a radial projection 12 near its free end, said projectionengaging in one of the slots 7 in the flange 6.

It will thus be seen that when a drive is imparted to the shaft 1 thisdriving torque will be transmitted to the shaft 2 through the slots 7,the projections 12, the bars 10 and the flange 4. The bar 10 is of amaterial and is so dimensioned to have a predetermined torque resistanceso that if the torque imparted to the shaft 1 by the prime mover iswithin predetermined upper and lower limits the bar it will remain rigidand the shaft 2 will be rotated at the same speed as the shaft 1.Should, however, the load on the transmission exceed or fall below theupper or lower predetermined limits respectively for which the torqueresistance of the bar it is selected the bar will twist in its bore 5,while its other end remains fixed in its hole 9, causing a relativerotational movement between the shafts 1 and 2.

The free end of the bar 10 is provided with a quick start thread 13meshing with a threaded member 14 secured to a flange 15 on a controlactuating member 16 freely surrounding the shaft 1. The end of themember 16 remote from the flange 15 is provided with a radially slottedring 17 and engaged in the slot 18 thereof is the nose 19 of a trunnion20 fixed with respect to the bearings (not shown) in which the shaftrotates. The trunnion has a projection 21 which can be connected to anymeans movable by a displacement of the trunnion. Should the bar 10 twistas aforesaid the member 16 will be moved axially with respect to theshaft 1 by the quick-start thread 13 while rotating with the shaft 2,and this axial movement of the member 16 will cause the projection 21 ofthe trunnion to be displaced and thus move a lever or other deviceoperatively connected to means for varying the load on the transmission.Such variation may vary the torque transl mitted by the driven member,or vary the load on or the output of the device, apparatus or the likedriven by the shaft 2. A cover 4a is attached to the member 4.

Referring to FIGURE 2 the conveyor comprises a conveyor casing 22 towhich pulverulent material carried in water is fed through a hopper 23;rotating in the casing 22 is an Archimedean spiral conveyor 24 supportedin bearings 25 at one end of the casing and in a spider 26 towards thedelivery end of the casing. The shaft 27 of the conveyor is connected toor forms the driven shaft 2 of a drive transmission (D) of the kindshown in FI URE 1, the shaft 1 of which is connected to a prime moversuch as an electric motor 28. The projection 21 of the trunnion 16 ofthe drive transmission is connected to a lever 29 pivoted to the frameof the apparatus so that its outer end, when the trunnion 16 is axiallydisplaced, will traverse an -arc in the direction of the arrows F,FIGURE 2, and this movement may vary the cur-rent supplied to the motor28 to vary the torque imparted to the shaft 27.

The outlet orifice of the conveyor casing 22 is provided by an annularflexible inflatable ring 30, of rubber for example. It will be seen thatby inflating the ring 30, or deflating it, the diameter of the orifice31 therethrough can be varied.

The ring is connected by a pressure line 32 to a pump 53 driven by aprime mover such as an electric motor 34. In the line 32 is a valve 35connected to the trunnion 16 as by a pivoted lever 36 and a rod 37 sothat axial movement of the trunnion will cause inflation or deflation ofthe ring 30 and thus affect the output of the conveyor.

Although the drive transmission of FIGURE 1 has been described withparticular reference in FIGURE 2 to a spiral conveyor it will beunderstood that it can be applied to any drive shaft or drivetransmission in which the variation of the load on the driving or drivenshafts or the output of the driven apparatus or the like needs continualadjustment automatically: for example, the drive transmission can beused in the drive of crushing mill rollers, where the pressure betweenthe crushing rollers sometimes rises to the breaking point of therollers, the torsional load on the drive shaft of the rollers increasingat the same time by employment of a drive transmission of the inventionin the drive shaft of the roller or rollers, the rising torsional loadin the shaft will result in the drive from the prime mover being cut outbefore the pressure between the rollers reaches the breaking point.

We claim:

1. A conveyor apparatus for pulverulent material suspended in liquid,said apparatus comprising a tubular conveyor casing, a rotatable spiralconveyor member within the casing, a hopper supplying the material to beconveyed to one end of the conveyor member within the casing, a variableoutlet orifice in the region of the other end of the casing, meansoperable to vary the size of said orifice, a drive member for rotatingthe conveyor member in the casing, a control device comprising at leastone twistable bar element having a portion fixed to one of said membersand held against twisting about its longitudinal axis and, spaced alongsaid axis from the fixed portion, a portion operatively connected to theother of said members and to a displaceable element capable of relativemovement with respect to the other of said members, the bar elementbeing calibrated to restrain movement of the displaceable element whensaid members are loaded Within at least one predetermined limit, butwhen said load exceeds said limit will twist thereby permitting relativeangular movement of one of said members with respect to the other memberin direct proportion to said excess load, and means associated with saiddisplaceable element and said orifice varying means so as to vary thesize of said orifice to cause reductioii of the load on said members towithin said predetermined limit.

2. A conveyor apparatus according to claim 1, wherein said bar elementis calibrated to restrain movement of said secured to the open deliveryend of the casing, a pump operable to pump fluid into said tube and torelease the fluid from said tube, a control valve between said pump andsaid tube and responsive to movement of the displaceable element so asto vary the size of the orifice by controlling the amount of fluid insaid tube.

References Cited in the file of this patent UNITED STATES PATENTS LumFeb. 18, 1941 2,554,796 Runninger May 29, 1951

